384P Prevalence of fibroblast growth factor receptor 2b (FGFR2b) protein overexpression in squamous non-small cell lung cancer (sqNSCLC)

FGFR2 contributes to tumor progression by enhancing angiogenesis and proliferation. In the randomized FIGHT Phase 2 study, the FGFR2b splice isoform, also called IIIb, was overexpressed in ∼30% of gastric cancers that were not known to be HER2+. Adding bemarituzumab, a first-in-class, anti-FGFR2b monoclonal antibody to mFOLFOX6 improved outcomes, indicating FGFR2b as a promising therapeutic target. There is limited data on FGFR2b prevalence in other tumor types and we report here its expression in sqNSCLC and the overlap with programmed death-ligand 1 (PD-L1).